Above: The Black Keys will close out the Firefly Music Festival in Dover on July 22.

The biggest rock festival ever to be staged in Delaware will be officially announced today, bringing a cavalcade of national acts to Dover this summer including headliners The Black Keys, The Killers and Jack White.

The three-day Firefly Music Festival will be held July 20-22 on the grounds near the Dover International Speedway in a wooded area usually known as RV Lot 10, but now dubbed the Woodlands by festival producers, Chicago-based Red Frog Events.

More than 40 acts will perform on four stages across 87 acres during the three-day weekend. Thirty-eight of the acts have been confirmed including R&B singer John Legend, psychedelic festival favorites The Flaming Lips and indie rockers Death Cab For Cutie. About seven more acts are expected to be added in the coming weeks.

Mike Tatoian, chief operating officer of Dover International Speedway, said officials hope the festival draws between 30,000 and 40,000 each day. It is planned to be an annual event, he said.

Tickets, available only as a three-day package, go on sale Thursday at noon through www.fireflyfestival.com. The pass will cost $178. On-site camping will be an option for festivalgoers, giving the three-day concert a familiar feel for music fans who have camped out at festivals like Bonnaroo Music and Arts Festival in Manchester, Tenn.

Headliners for each day have been already assigned: former White Stripes frontman Jack White fronts Friday, The Killers close out Saturday and The Black Keys, which sold out both Madison Square Garden in New York and Wells Fargo Center in Philadelphia last month, wrap up the festival Sunday.

For Delaware rock fans, the size and scope festival goes beyond anything they could have even dreamed up themselves. Before hearing the news about Firefly, Wilmington music fan Brad Wallace, 28, had planned to pay $259 for a four-day pass to attend Bonnaroo in June. After hearing the line-up of acts playing right in his home state this summer, Wallace was nearly speechless before declaring that might not go to Tennessee after all.

“Are you kidding me? That’s a knock-out line-up,” said Wallace, whose Wilmington-based CineMavericks Media company occasionally books local concerts in Delaware. “This something the state has been waiting for musically for a very long time. You just made my day. That’s one of the most incredible things I’ve heard.”Above: Jack White will headline the opening day of the new Firefly Music Festival near the Dover International Speedway on July 20.

It will be the first major festival produced by Red Frog Events, which has been hosting large-scale foot races nationwide since its inception in 2007. Lamda Productions, the company that has provided the entire production team for Bonnaroo each year it has been held, will do the same for Firefly, a name chosen to give the feeling of a carefree, summer night, officials said.

Firefly will have plenty of competition that summer weekend. Not only is it the opening weekend of the Delaware State Fair in nearby Harrington, but also the weekend of WXPN 88.5-FM’s XPoNential Music Festival in Camden N.J.

Firefly Music Festival Director Greg Bostrom said Dover was chosen out of a field of 60 sites, nine of which company officials visited. Dover was selected, he said, because of the speedway staff, its space and its proximity to large East Coast cities like New York, Philadelphia, Baltimore and Washington, D.C. The area’s proven ability to handle large crowds on race weekends and the availability of hotels also helped, he said.

“It’s a lush, picturesque wooded setting with a lot of grass and a lot of trees,” Bostrom said. “We hope to be the premier East Coast music experience that will start in 2012 and we’re hoping continues for many years to come.”

Based on crowd estimates, the state’s director of tourism, Linda Parkowski, said the economic impact of the festival should generate an estimated $12.6 million in additional direct spending in the state by festivalgoers.

“This is going to be huge for Delaware,” she said. “This is going to generate a lot of excitement and really raise the visibility for Delaware.”

In addition to the music, organizers promise everything from craft beers and multiple food options from vendors to a wine garden and hot air balloon rides on site. Dover International Speedway’s Tatoian said racetrack officials were first approached about possibly hosting the festival in the fall. He said Red Frog were the ones who proposed the wooded grounds near the speedway as the location.

“This will be an annual event just like all the other great festivals like Bonnaroo, Coachella and Lollapalooza,” Tatoian said. “We want this festival to be on that map.”

The last time Jack White performed in Delaware, it was 2007 when The White Stripes performed at The Grand in Wilmington. It was his first-ever concert in the state, unfurling an instantly legendary show, which turned out to be one of his last with the Grammy-winning group, which disbanded soon after. Even the man who booked that show was bowled over by news of Firefly.

“Wow. That’s pretty big. Certainly in the time I’ve been here, I’ve never seen anything proposed that’s this big,” Steve Bailey, executive director of The Grand for nearly 15 years, said after hearing about the festival’s line-up. “As Delaware finally gets a face or a brand to it, this is the kind of stuff you can expect to see happen here. This is nothing but good. It’s just too cool.”

Above: The Killers will close out the July 21 line-up of the three-day Firely Music Festival making its debut in Dover this summer.

IF YOU GOWhat:Firefly Music FestivalWhen: July 20, 21 and 22Where: On the grounds near Dover International Speedway, 1131 U.S. 13, DoverTickets: $178 for a three-day pass. Tickets go on sale Thursday at noon.